corrected the contributing.md guide link

[swastik959]

Closes #49

📑 Description

✅ Checks

• [ ] My pull request adheres to the code style of this project
• [ ] My code requires changes to the documentation
• [ ] I have updated the documentation as required
• [ ] All the tests have passed

ℹ Additional Information

[thschue]

@swastik959 : Please fix DCO to get this merged :-)

[swastik959]

@thschue done